17,723 research outputs found

    Radial distribution of RNA genome packaged inside spherical viruses

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    The problem of RNA genomes packaged inside spherical viruses is studied. The viral capsid is modeled as a hollowed sphere. The attraction between RNA molecules and the inner viral capsid is assumed to be non-specific and occurs at the inner capsid surface only. For small capsid attraction, it is found that monomer concentration of RNA molecules is maximum at the center of the capsid to maximize their configurational entropy. For stronger capsid attraction, RNA concentration peaks at some distance near the capsid. In the latter case, the competition between the branching of RNA secondary struture and its adsorption to the inner capsid results in the formation of a dense layer of RNA near capsid surface. The layer thickness is a slowly varying (logarithmic) function of the capsid inner radius. Consequently, for immediate strength of RNA-capsid interaction, the amount of RNA packaged inside a virus is proportional to the capsid {\em area} (or the number of proteins) instead of its volume. The numerical profiles describe reasonably well the experimentally observed RNA nucleotide concentration profiles of various viruses.Comment: 5 pages, 2 figures. Abstract, introduction rewritten. Comparison to actual virus profiles added. Submitted to PR

    Effect of prednisolone on inflammatory markers in pericardial tuberculosis: A pilot study

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    Background: Pericardial disorders are a common cause of heart disease, and the most common cause of pericarditis in developing countries is tuberculous (TB) pericarditis. It has been shown that prednisolone added to standard anti-TB therapy leads to a lower rate of constrictive pericarditis. We conducted a pilot study to evaluate the effect of adjunctive prednisolone treatment on the concentration of inflammatory markers in pericardial tuberculosis, in order to inform immunological mechanisms at the disease site. Methods: Pericardial fluid, plasma and saliva samples were collected from fourteen patients with pericardial tuberculosis, at multiple time points. Inflammatory markers were measured using multiplex luminex analysis and ELISA. Results: In samples from 14 patients we confirmed a strongly compartmentalized immune response at the disease site and found that prednisolone significantly reduced IL-6 concentrations in plasma by 8 hours of treatment, IL-1beta concentrations in saliva, as well as IL-8 concentrations in both pericardial fluid and saliva by 24 hours. Conclusion: Monitoring the early effect of adjunctive immunotherapy in plasma or saliva is a possibility in pericarditis

    Does higher education foster critical and creative learners? An exploration of two universities in South Korea and the USA

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    This paper describes two studies that explore students' beliefs about critical and creative learning at two universities, and considers the implications of those beliefs in comparison to the universities' stated education goals. One is a mixed method study of students at a top university in Korea, and the second is a comparative study between the Korean university and a United States (US) university. The first study found that both high-achievers and the general population at a top Korean university perceived their critical and creative abilities as lower than their receptive learning abilities, and that higher achievers were neither more critical nor creative than lower achievers. The second study finds that the Korean university students, compared to US students, were more likely to rate their receptive learning ability as higher than their critical and creative learning abilities. Comparisons across year of higher education (HE) suggest that Korean students' perceptions did not significantly change with respect to year in school, while US students' perceptions of critical learning abilities significantly increased across school years. Results are discussed with respect to the impact of culture, epistemological beliefs, and HE instruction on critical and creative learning

    Heavy pseudoscalar-meson decay constants with strangeness from the extended nonlocal chiral-quark model

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    We study the weak-decay constants for the heavy pseudoscalar mesons, D, Ds, B, and Bs. For this purpose, we employ the extended nonlocal chiral-quark model (ExNLChQM), motivated by the heavy-quark effective field theory as well as the instanton-vacuum configuration. In addition to the heavy-quark symmetry and the nonlocal interactions between quarks and pseudoscalar mesons in ExNLChQM, a correction for the strange-quark content inside Ds and Bs is also taken into account and found to be crucial to reproduce the empirical values. From those numerical results, we obtain f_{D,Ds,B,Bs}=(207.53, 262.56, 208.13, 262.39) MeV, which are in good agreement with experimental data and other theoretical estimations. Using those numerical results, we compute the CKM matrix elements and the Cabibbo angle, using various mesonic and leptonic heavy-meson decay channels, resulting in (|V_{cd}|,|V_{cs}|,|V_{ub}|,|V_{td}|/|V_{ts}|)=(0.224,0.968,<5.395*10^{-3},0.215) and theta_C=12.36^o which are well compatible with available data.Comment: 12 pages, 7 figures, accepted for publication in Mod. Phys. Lett.

    Forest Carbon Sequestration under the U.S. Biofuel Energy Policies

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    This paper analyzes impacts of the U.S. biofuel energy policies on the carbon sequestration by forest products, which is expressed as Harvested Wood Products (HWP) Contribution under the United Nations Framework Convention on Climate Change. Estimation for HWP Contribution is based on tracking carbon stock stored in wood and paper products in use and in solid-waste disposal sites (SWDS) from domestic consumption, harvests, imports, and exports. For this analysis, we hypothesize four alternative scenarios using the existing and pending U.S. energy policies by requirements for the share of biofuel to total energy consumption, and solve partial equilibrium for the U.S. timber market by 2030 for each scenario. The U.S. Forest Products Module (USFPM), created by USDA Forest Service Lab, operating within the Global Forest Products Model (GFPM) is utilized for projecting productions, supplies, and trade quantities for the U.S. timber market equilibrium. Based on those timber market components, we estimate scenario-specific HWP Contributions under the Production, the Stock Change, and the Atmospheric Approach suggested by Intergovernmental Panel on Climate Change (IPCC) Guidelines for National Greenhouse Gas Inventories using WOODCARB II created by VTT Technical Research Centre of Finland and modified by USDA Forest Service Lab. Lastly, we compare estimated results across alternative scenarios. Results show that HWP Contributions for the baseline scenario in 2009 for all approaches are estimated higher than estimates reported by U.S. Environmental Protection Agency in 2011, (e.g., 22.64 Tg C/ year vs 14.80 Tg C/ year under the Production Approach), which is due to the economic recovery, especially in housing construction, assumed in USFPM/GFPM. Projected HWP Contribution estimates show that the Stock Change Approach, which used to provide the highest estimates before 2009, estimate HWP Contribution lowest after 2009 due to the declining annual net imports. Though fuel wood consumption is projected to be expanded as an alternative scenario requires higher wood fuel share to total energy consumption, the overall impacts on the expansion in other timber products are very modest across scenarios in USFPM/GFPM. Those negligible impacts lead to small differences of HWP Contribution estimates under all approaches across alternative scenarios. This is explained by the points that increasing logging residues are more crucial for expansion in fuel wood projections rather than the expansion of forest sector itself, and that the current HWP Contribution does not include carbon held in fuel wood products by its definition.Forest Products, Carbon Sequestration, Biofuel Policies, HWP Contribution, Resource /Energy Economics and Policy,

    Characterization of the Interaction between the Herpes Simplex Virus Type I Fc Receptor and Immunoglobulin G

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    Herpes simplex virus type I (HSV-1) virions and HSV-1-infected cells bind to human immunoglobulin G (hIgG) via its Fc region. A complex of two surface glycoproteins encoded by HSV-1, gE and gI, is responsible for Fc binding. We have co-expressed soluble truncated forms of gE and gI in Chinese hamster ovary cells. Soluble gE-gI complexes can be purified from transfected cell supernatants using a purification scheme that is based upon the Fc receptor function of gE-gI. Using gel filtration and analytical ultracentrifugation, we determined that soluble gE-gI is a heterodimer composed of one molecule of gE and one molecule of gI and that gE-gI heterodimers bind hIgG with a 1:1 stoichiometry. Biosensor-based studies of the binding of wild type or mutant IgG proteins to soluble gE-gI indicate that histidine 435 at the CH2-CH3 domain interface of IgG is a critical residue for IgG binding to gE-gI. We observe many similarities between the characteristics of IgG binding by gE-gI and by rheumatoid factors and bacterial Fc receptors such as Staphylococcus aureus protein A. These observations support a model for the origin of some rheumatoid factors, in which they represent anti-idiotypic antibodies directed against antibodies to bacterial and viral Fc receptors

    Study of orientation effect on nanoscale polarization in BaTiO3 thin films using piezoresponse force microscopy

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    We have investigated the effect of texture on in-plane (IPP) and out- of plane (OPP) polarizations of pulsed-laser-deposited BaTiO3 thin films grown on Pt and La0.5Sr0.5CoO3 (LSCO) buffered Pt electrodes. The OPP and IPP polarizations were observed by piezoresponse force microscopy (PFM) for three-dimensional polarization analyses in conjunction with conventional diffraction methods using x-ray diffraction and reflection high energy electron diffraction measurements. BaTiO3 films grown on Pt electrodes exhibited highly (101) preferred orientation with higher IPP component whereas BaTiO3 film grown on LSCO/Pt electrodes showed (001) and (101) orientations with higher OPP component. Measured effective d(33) values of BaTiO3 films deposited on Pt and LSCO/ Pt electrodes were 14.3 and 54.0 pm/ V, respectively. Local piezoelectric strain loops obtained by OPP and IPP-PFM showed that piezoelectric properties were strongly related to film orientation
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